[SkyBelow]

>there were a number of classmates whom could not grasp the idea of plagiarism being unethical

It might help to define what form of plagiarism you encountered as there are some behaviors that count as plagiarism (at least were counted as such back in my college ethics class) which I never found any valid reasoning for. I have no difficulty understanding the ethical issues of passing off someone else's work as your own, but you can also plagiarize by passing off your own work as your own.